The invention relates to a protection device for a circular saw blade in a circular saw machine having a tiltable saw assembly.
Protection devices for such circular saw machines are known in which one part forms a cover which can be fixed to the saw assembly, partly accommodates the circular saw blade in itself, and engages over approximately one half of the blade at both sides. The other part screens the remainder of the accessible side of the blade as well as the peripheral portion which is located at the operating end, in that it embraces the said portion. In order to provide in this case good visibility in the working region of the circular saw blade, this part of the device consists of a transparent synthetic resin material. Moreover it is adjustable relative to the height of the cover, in that it is arranged to be rotatable about an axis, in order to ensure upon tilting of the saw assembly that this member remains always in the same position relatively to the cutting location when the sawing advance is being performed.
The known protection device thereby ensures effective protection against contact with the freely accessible face of the circular saw blade and with the operating end.
However, on the other side of the saw assembly the portion of the blade which projects downwardly from the assembly is freely accessible; for this reason this kind of construction does not satisfy current standards for treatment and processing machines which prescribe inter alia that, in the rest position of the circular saw blade, access to the cutting portion must not be possible, and that, in the working position, only that portion of the saw blade is to be released which is used for cutting.
Therefore, what is desired is a protection device which satisfies these standards.
The present invention provides a protection device for a circular saw blade in a circular saw machine having a tiltable saw assembly which comprises a horizontal saw shaft and which is tiltable about a horizontal pivot axis for the purpose of performing the saw advance, the protection device comprising a first part and a second part which, in a starting position of the saw assembly, together cover the circular saw blade from above at its freely accessible side face and at least at the peripheral portion which is present at the operating side, the first part being arranged stationarily on the saw assembly and the second part being arranged to be adjustable parallel to the first part, the said first part embracing the circular saw blade at least from behind and extending substantially as far as the lower peripheral region, the said second part forming a cover which engages over the circular saw blade and which, in the starting position of the saw assembly, surrounds the circular saw blade at the upper peripheral portion and at the peripheral portion which is present at the operating side, at least as far as the vicinity of the lower peripheral portion or the cutting location, the device including control means by which the second part is adjustable relative to the first part, during tilting of the saw assembly, in such a manner that, in each phase of the tilting movement of the saw assembly, the second part retains substantially the same position in space relative to a horizontal plane.
In a protection device constructed in this manner the circular saw blade is covered at least in the peripheral region and laterally to such extent that in the starting position of the saw assembly unintentional entry into the cutting portion is no longer possible.
In this case the control means associated with the cover ensures that in each phase of the saw advance and in spite of the pivotal movement of the saw assembly the cover substantially maintains its position in the vertical plane. It is attained thereby that nevertheless the cover may be displaced relatively to the cutting location in the direction in which the saw slot extends, owing to the pivotal movement of the saw assembly, that in this case, however, during sawing, neither a collision with the work clamping device or the workpiece, nor a displacement is possible such that the circular saw blade becomes accessible from one or both end faces in the peripheral region, from the operating end or from the end located opposite thereto.
A further advantage is that at least in the rest position the movable part of the protection device is retained in such a manner that it is protected against unintentional lifting and the saw blade is released only during movement of the saw assembly to the working position.
It is advantageous in this case for the cover to be locked by the control means, in the starting position of the saw assembly, so that additional auxiliary means may be omitted.
The displaceable part of the protection device formed by the cover may be vertically adjustable relatively to the saw assembly or rotatable about a pivot axis. In either case it is advantageous to construct the control means in such a manner that the cam-following member provided in accordance with this claim and co-operating with a control cam may be used, also for locking the cover, in the starting position of the saw assembly, the cam-following member engaging in an appropriate recess in the control cam.
A further improvement provides that the cover is retainable in its release position and returns automatically to its covering position upon displacement of the saw assembly. This unlocking of the cover may be performed in a simple manner in that it is retainable in its release position by means of an abutment member which is arranged to be displaceable from an abutment position to a release position, preferably on a manual lever of the saw assembly; this abutment member then necessarily releases the cover upon displacement of the saw assembly.
In as much as a tiltable circular saw machine is involved the saw assembly of which is pivotal on the machine frame in such a manner that, during its movement between the two pivotal end positions theref, the circular saw blade is guided substantially from behind to a workpiece clamping device, a favourable construction is obtained. If, in contrast, the pivotal assembly is displaceable along a circular arc portion extending from the top to the bottom during its pivotal movement in the direction of the workpiece, an advantageous construction of the protection device is attainable. In this case the circular saw blade is substantially completely covered at its freely accessible face in the rotation starting position of the saw assembly, and the cover may be so constructed that the circular saw blade is completely embraced by the cover at its face adjacent the saw assembly, at least in the peripheral region as far as its lower peripheral portion, so that then in co-operation with the part of the protection device secured to the saw assembly the circular saw blade is accommodated completely encapsulated in the protection device.
A further advantageous variant of this kind of construction resides in that the part of the protection device which is secured to the saw assembly is so constructed that it engages over the circular saw blade likewise at the upper peripheral portion thereof. Thereby a particularly safe arrangement is made which provides a more reliable protection when torn saw blades fly out.